No one is watching the walls

Published 11:18 am, Wednesday, February 3, 2010

A 'gravity wall' like the one at Rivermist relies on its own weight to remain stable.

A 'gravity wall' like the one at Rivermist relies on its own weight to remain stable.

No one is watching the walls

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Editor's note: This story originally appeared Sunday, Jan. 31, exclusively in the print edition of the San Antonio Express-News.

Despite the growing popularity of towering retaining walls like the one that buckled last week, San Antonio officials have paid scant attention to the structures in residential subdivisions and can’t vouch for their safety.

No one at City Hall tracked how many walls were built over the years as thousands of residents flocked to the Texas Hill Country and developers reshaped steep terrain for new homes.

City inspectors never checked the walls.

And, according to members of the real estate industry, it wasn’t widely known that a permitting process existed for tall retaining walls. “No one can find where the city has ever asked for or insisted on a permit,” subdivision developer Norman Dugas said. “I can’t find anyone who has ever gotten one.”

Sanchez’s office provided an example of a housing project in the Dominion where homebuilder Toll Brothers had sought a proper permit for a retaining wall.

But officials acknowledged there’s an untold number of retaining walls in the city that were built without permits, which means there’s no easy way to tell if the structures were properly designed by an engineer and built to those specifications.

Mayor Julián Castro pledged city staff will be scrutinizing retaining walls in the future. When asked how safe existing walls are, Castro acknowledged it’s a difficult question to answer.

“There’s certainly cause for concern,” Castro said.

A growing trend

The real estate industry says the structures are safe. Centex Homes, which developed The Hills of Rivermist where 91 homes were evacuated last week, stated the collapse was an isolated event caused by “unique” soil conditions at the site.

The company’s public statement blamed the collapse on “significant soil shift on the slope which resulted in the eventual damage to portions of the retaining wall.” Huge retaining walls like the one at Rivermist are easy to spot on the hilly North Side. To create more level lots that save costs on concrete for home foundations, developers sculpt hills into terraces with retaining walls. Sometimes, developers stack the terraces like layers of a wedding cake.

The mass-grading technique can allow a developer to squeeze more lots into a subdivision and create flatter, more usable space in yards. Many walls are two stories or taller and homes often are built right next to them.

After hearing about the problems at Rivermist, Steve Birdsall wondered about the stability of a two-story terrace across the street from his house at Encino Ridge near Stone Oak Parkway and U.S. 281. The sheer wall built by Pulte Homes is composed of a layer of limestone bedrock, with a retaining wall on top.

“When I first heard it on the news, I wondered if a collapse could happen here,” said Birdsall, 41, who lives in the 21000 block of Dolomite Drive.

As a renter, Birdsall said he’s not too worried about the property — but it’d be a different story if he owned the house.

Atop the tall terrace across the street from Birdsall’s house live Mohsen Ebrahimi, 52, and his family. Their backyard ends in a sheer drop, and a wooden privacy fence prevents anyone from taking a wrong step.

“These are pretty tall walls,” Ebrahimi said as he stood on his deck, soaking in the view. “You see that two-story house? The top of that house reaches my backyard.”

Pulte Homes spokeswoman Valerie Dolenga said the retaining walls at Encino Ridge are primarily decorative, unlike the wall that collapsed at Rivermist, and the company is unaware of any problems.

Dolenga said homeowners at Encino Ridge met with Pulte representatives last week to ask the company about the retaining walls.

“They wanted to see plans and permits, and — at this point — we don’t have those,” Dolenga said.

Permit required?

After last week’s wall collapse, City Manager Sheryl Sculley sent an e-mail to the mayor and the City Council to update them on the incident.

“The hillside collapse within the Rivermist subdivision was the result of an improperly constructed retaining wall and the improper compaction of fill on which homes were constructed,” Sculley wrote. “The developer did not obtain the required permits.” The city announced publicly that Centex failed to pull a permit for the wall, and that Centex should have submitted plans designed by a licensed engineer as part of the permit review process.

Centex officials said they didn’t know a permit was required for a retaining wall. They weren’t alone.

Engineer Gene Dawson Jr. of Pape-Dawson Engineers, which designed the lot and street layout of Rivermist, said retaining walls for commercial developments require permits. But he’s never heard of permits being needed for walls in residential developments.

Don Durden, an engineer in San Antonio since 1977, didn’t know about the permitting requirements either.

Durden said retaining walls long have been a feature of San Antonio neighborhoods, which rarely are completely level. To deal with drainage and create more usable yard space, developers typically sloped the land between houses or used railroad ties to create small retaining walls between 1 and 4 feet high — a landscape feature instead of an engineering feat.

As the city grew and land prices rose, however, homebuyers pushed farther into the Hill Country. The slopes people built homes on became more extreme — along with the retaining walls. Durden and other developers said they thought there was no city process in place to regulate the retaining walls.

“The process wasn’t set up and didn’t evolve,” Durden said.

A reporter asked city officials Tuesday for any examples of a developer or builder who followed the proper process and applied for a building permit for a retaining wall. Friday morning, the city provided paperwork for a segment of the Dominion by homebuilder Toll Brothers.

The city also found building permits for four homes in another project that were put on hold because a permit application for a nearby retaining wall hadn’t been submitted by the builder.

Finding the permits was difficult work. Richard Chamberlin, a city engineer who helped search for the documents, said the city’s computer system doesn’t specifically track them.

“It’s really hard to say how many retaining walls got permits and how many didn’t, because it’s so hard to find them in the system,” Chamberlin said.

The permitting requirements are part of the city’s residential building code. Those standards apply to structures usually built at later stages of the development process. But retaining walls often are constructed at early stages when developers grade and level the ground for new homes that have yet to be built.

At that stage, developers follow a set of city standards known as the Unified Development Code, which governs things like lot densities and street layouts. Those standards don’t mention permits for retaining walls in neighborhoods.

“Here, I think, is where the gap occurs, Dawson said. “The developer deals with the Unified Development Code. He tries to comply with those regulations. And there’s nothing in those regulations that say if you build retaining walls for your mass earth-work, you need to come get a building permit.”

The next step

Austin has stringent guidelines about using retaining walls and building on slopes — measures put in place years ago to protect the city’s watershed.

Retaining walls need permits and go through a city inspection in Austin, even if they are on private property.

“There’s nothing to preempt someone from doing a structural wall, but you have a hurdle if you go over 4 feet,” said Pat Murphy, the environmental officer for the city. And Austin limits the amount of cutting and filling that can happen on a site to 4 feet.

“You can have more than that if you have a variance,” Murphy said. “It severely hampers a developer from changing the landscape.” Dan Woodard lives off of Kyle Seale Parkway north of Loop 1604 and has a retaining wall running along his property. He’s comfortable with how the wall was built and even has requested that Pulte add a wall to a neighboring property now under construction.

But Woodard said he saw a retaining wall near the front of his neighborhood fail in 2008. “It blew water and rocks across the median between the two roads,” he said. “We couldn’t get out on that side of the street. You could not drive past it.”

He wants to know what the city plans to do now.

“My question to the city is, going forward, are we going to inspect the retaining walls?” Woodard said “They’ve got to start using the right building practices as they move farther and farther into the hills.” City officials acknowledge they haven’t closely paid attention to all retaining walls in the past. But they say that’s going to change.

“We need to improve the process,” said T.C. Broadnax, assistant city manager who oversees development issues. That could possibly mean higher costs to deal with the increased workload of scrutinizing future retaining walls, Broadnax said.

And Broadnax and other officials said they need to do a better job informing the development community about the city’s permitting standards.

“Moving forward,” Mayor Castro said, “the city will ensure the standards are very well known and abided by builders.”